The 4th Generation (4G) mobile communication system is deigned with the underlying ideas of a linear receiver and orthogonal transmission. The linear receiver is adopted because the linear receiver is easy to implement in engineering while guaranteeing the performance thereof; and orthogonal transmission is adopted so that a receiver can be easy to implement in engineering due to orthogonal transmission. FIG. 1 is a schematic diagram of the orthogonal design where different data are transmitted respectively over orthogonal physical resources in such a way that each of the data is transmitted over corresponding each of the physical resources, and the respective data are orthogonal without any interference to each other.
The capacity of a multi-user transmission system is out of reach by the orthogonal system due to a limited number of radio resources. A drawback in orthogonal transmission of data lies in a low capacity of the system, i.e., a low data transmission capacity of the system.
At present, a non-orthogonal multi-access mode has become possible based on energy allocation principle as proposed by NTT DoCoMo Corp (see WO2012161080), and although there is a performance gain relative to the orthogonal system, energy may not be allocated freely, so the capacity of the system may still be insufficient, and the data transmission capacity of the system may still be low.